Foldable invalid chair

ABSTRACT

A foldable invalid chair, comprising two hingedly connected side frames provided with bearings for the mounting of axles of driving wheels and dirigible wheels, the driving wheels being in the form of running wheels mounted on the side frames. A detachable propulsion unit, including an electric motor is positioned between the side frames, and is coupled to the axles of both driving wheels.

United States Patent [1 1 Meyer Nov. 6, 1973 1 FOLDABLE INVALID CHAIR [76] Inventor: Wilheilm Meyer, 3

Kleinbahnhofstrasse, 4973 Vlotho,

G ny 7. e.

[22] Filed: Mar. 30, 1971 [21] Appl. N0.: 129,424

Related US. Application Data [63] Continuation-impart of Ser. No. 862,210, Sept. 30,

1969, abandoned.

[30] Foreign Application Priority Data Oct. 1, 1968 Austria 9558 [52] US. Cl. 180/65 R, ISO/DIG. 3, 180/25 A, 180/70 R [51] Int. Cl. B60k 1/00 [58] Field of Search 180/65, DIG. l, DIG. 2, ISO/DIG. 3, 27, 25 A, 70 R, 88; 69/10 [56] References Cited UNITED STATES PATENTS 2,798,565 1/1957 Rosenthal et a1. ISO/DIG. 3

9/1922 Gladish 180/65 X 3,103,384 9/1963 Zivi 297/D1G. 4 2,765,860 10/1956 Church 180/D1G. 3 2,423,568 7/1947 Slowig 64/10 X 909,411 1/1909 Hockney 297/D1G. 4 2,431,112 11/1947 Everest et a1. 180/D1G. 3 2,426,365 8/1947 Matlock 180/70 R X 2,544,831 3/1951 Guyton 180/65 R X Primary Examiner-Kenneth H. Betts Assistant ExaminerJohn P. Silverstrim Attorney-Sughrue, Rothwell, Mion', Zinn & MacPeak [57] ABSTRACT A foldable invalid chair, comprising two hingedly connected side frames provided with bearings for the mounting of axles of driving wheels and dirigible wheels, the driving wheels being in the form of running wheels mounted on the side frames. A detachable propulsion unit, including an electric motor is positioned between the side frames, and is coupled to the axles of both driving-wheels.

5 Claims, 9 Drawing Figures PATENTEUNUV 6l975 3770.073

SHEET 30F 4 FOLDABLE INVALID CHAIR This application is a continuation in part application of copending application Ser. No. 862,210 filed Sept. 30, 1969, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an invalid chair for handicapped persons.

2. Description of the Prior Art Various forms of motor powered invalid chairs have been attempted in the prior art with limited degrees of success. Generally they are not capable of being readily foldable and have permanently attached power units. Basic problems are usually present with their complexity and lack of efficiency both from a mechanical and economical viewpoint.

SUMMARY OF THE INVENTION An object of the invention is to provide a selfpropelled foldable invalid chair which is fitted with a propulsion unit including a primer mover such as an electric motor.

Another object of the invention is to provide an invalid chair with a readily removable and very efficient propulsion unit.

A further object consists in providing an invalid chair with an electrically operated propulsion unit which may be braked quickly to ensure an emergency stop.

According to the present invention, an invalid chair comprises two hingedly connected side frames provided with bearings for the mounting of axles of driving wheels and dirigible wheels, the driving wheels being in the form of running wheels mounted on the side frames, a detachable propulsion unit comprising an electric motor and positioned between the side frames, being coupled to the axles of both driving wheels.

In a preferred embodiment of the invention the propulsion unit comprises a driven shaft arranged between and coaxial with the axles of the driving wheels, the driven shaft being detachably connected by means of endside coupling parts to corresponding coupling parts mounted on the driving wheel axles.

In a further preferred embodiment the coupling provided in each side region of the invalid chair is enclosed by a turnbuckle formed of two hinge-like interconnected shells provided as a support and cover shell, one shell thereof, preferably the lower support shell, being rigidly mounted on the adjacent frame.

In accordance with a further feature of the invention the shaft of the electric motor is provided with a quickly acting brake device having a brake shoe engaging at least partly around a brake surface mounted on the motor shaft and connected with an operating lever.

Such an invalid chair is of simple structure and, due to its having a removable propulsion unit, it can be folded if required; due to the direct coupling of the propulsion unit and driven shaft with both driving wheels the chair has a considerable degree of efficiency, so that a perfect utilization of energy is ensured. The brake acting on the shaft of the electric motor ensures a speedy braking of the movement of the invalid chair.

In a further embodiment of the present invention two clutches having a resilient coupling member are located between the frames and propulsion drive. Therefore, when the brake is suddenly applied to the wheel chair, the first vibration is received by the resilient coupling members and then transmitted in an attenuated condition to the propulsion drive and transmission gear, with the result that the propulsion drive is subjected to a reduced load with the sudden application of the brake. The torsion forces resulting from the braking action are preferably partially received by the couplings. Such a coupling with its extremely favorable mode of operation is also simple to design and economical to construct.

Due to the resilient coupling members, the entire wheel chair has a favorable degree of flexibility which makes it possible for comparatively steep inclines (approximately 7-9) to be ascended or descended.

Between the frames of the invalid wheel chair a stabilizer rod keeping the two frames at a space from each other, is detachably arranged and is articulated at both ends and hinged to the frames. This rod makes the wheel chair flexible in this region, and in addition, the rod helps to ensure the gauge of the wheel chair.

Due to the resilient coupling members, the entire vehicle has a favorable degree of flexibility. This flexibility is very important, since it is very often necessary to use the electric wheel chair on bad roads or sidewalks. In order to prevent the chair tipping over on these journeys, the entire driving gear suspension is made flexible. It is important that, when travelling over these uneven stretches, all the four wheels should be in contact with the ground. In order to achieve this, not only the entire clutch, but also scissor-action rods are flexibly constructed so that the side frames can be swung upwardly relative to each other.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is an end view of an invalid chair constructed in accordance with the invention having a propulsion unit arranged between lateral frames coaxially with the axles of the driving wheels;

FIG. 2 is a longitudinal section through the coupling side connecting region between the propulsion unit and wheel axles;

FIG. 3 is a side view of a braking device co-operating with the propulsion unit;

FIG. 4 is an end view of the same propulsion unit with the wheel axles in the coupled state;

FIG. 5 is a front view of a foldable invalid chair constructed in accordance with a further embodiment of the present invention;

FIG. 6 is a front view of the chair of FIG. S,'show,ing the region of the driving wheels with the propulsion drive provided between the side frames and coupled to the driving axles;

FIG. 7 is a partial section through a clutch provided between the driving axle and one end of the driving shaft of the propulsion drive, with axially displaceable clutch pins, in the engaged position;

FIG. 8 is a partial section through a plan view of the clutch as claimed in FIG. 7; and

FIG. 9 is a partial section through a front view of the other clutch provided between the driving axle and the other end of the propulsion drive shaft of the wheel chair of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT The foldable invalid chair shown in FIG. 1 has two lateral frames 10, 11 retained with variable spacing relative to one another, which receive two driving wheels 13 rotatable about their axles 12, in their respective front regions and two dirigible wheels (not shown in FIG.- 1) of smaller diameter relative to the driving wheels 13, in their respective rear regions. A propulsion unit 14 is detachably coupled with the axles 12, of the driving wheels 13, between the two lateral frames 10,11. The unit 14 comprises a prime mover, such as an electric motor 19 and a gear 16 connected to a shaft, which gear 16 is coaxial to the wheel axles 12 and a shaft 15 driven from the prime mover 19.

The driven shaft 15 of the gear 16 is connected to the propulsion unit 14 is provided with a coupling part 17 at both end regions, each part 17 being detachably connected to a coupling part 18 of the wheel axles 12. The propulsion unit 14, together with the driven shaft 15 of the gear 16 can, by means of the coupling parts 17, be pulled out upwardly and forwardly from the coupling parts 18 of the wheel axles 12. When the driving shaft position is at right angles to the axles 12, the propulsion unit 14 can be separated from the invalid chair by being pulled out as the clearance between the driving shaft and the axles 12 is variable.

The driven shaft 15, is provided with claw-like coupling parts 17 which engage in corresponding counter coupling parts 18 of the wheel axles 12. The wheel axles 12 are each mounted by means of roller bearings 20 in a bearing bush 21 rigidly mounted on the frame 10, 11 by welding. The coupling part 18 projecting from the inwardly directed surface of each wheel axle 12, is non-rotatably secured against displacement relative thereto.

the coupling part 18 of each wheelaxle 12 has a centering projection 22 such as a square boss which retains the wheel axles 12 axially in line with the driven shaft 15; the centering projection 22 of each wheel axle 12 is thus resiliently located on the end face of the wheel axle by means of a spring element 23, such as a plastics material or a rubber block and, due to its yielding arrangement allows the coupling parts 17, 18 to be joined together and to be readily connected.

A clamping device 26, formed of two hingedly interconnected shells comprising a supporting shell 24 and a cover shell 25, is arranged around the coupling provided in each side region of the invalid chair, formed of the two interengaging coupling parts 17, 18 of the driving shaft 15 and the wheel axle 12. One shell, preferably the lower supporting shell 24, is rigidly located on the adjacent frame 10, 11 by welding.

The lower supporting shell 24 of the device 26 acts as a support and the upper cover shell acts as an abutment for a hollow shaft 27 enclosing the driven shaft 15. The two shells 24, 25 engage in an annular groove of the hollow shaft 27 by means of end face fixing flanges 28 and are reinforced on the coupling side by means of a shoulder or bearing and adapted to be connected with one another to form a cylindrical hollow body.

Each coupling side end region of the hollow shaft 27 is provided with roller bearings 29 and the driven shaft 25 is rotatably mounted therein. The hollow shaft 27 is rigidly connected to the gear 16 and supports the propulsion unit 14 comprising the gear 16 and the prime mover 19, the hollow shaft 27 itself being supported on the lower supporting shells 24. The propulsion unit 14, also comprising the driven shaft 15, is detachable from the wheel axles 12.

A support 30, such as a shell is provided on the prime mover 19 and abuts a shoulder 31, such as a tubular socket mounted on the lateral frame 11. In this way the propulsion unit 14 is positionally located between the two frame 10 and 11 and is prevented from rotating about the driven shaft 15.

A motor shaft 33 of the prime mover 19 is provided with a quick-action brake device 34 which is connected to an operating lever 35 of the prime mover. The brake device 34 is formed by a brake shoe 38 engaging at least partly about a brake surface 36, such as a brake drum or axle journal reinforcement of the motor shaft 33 and is connected to the motor operating lever 35 by means of a linkage 37, such as a Bowden cable, which brake shoe, by means of a compression spring 39, is kept constantly under spring pressure in the braking position.

When the prime mover 19 is switched on, the linkage 37 connected to the motor operating lever 35 is varied in length and the compression spring 39 is compressed by the linkage 37, whereby the brake shoe 38 is lifted off the brake surface 36. When the motor 19 is switched off, the compression spring 39 presses the brake shoe 38 against the brake surface 36 so that, by preventing the motor shaft 33 from continuing to run or running down, the prime mover 19 is stopped immediately.

The propulsion unit 14 has a handle 40 to provide a grip during detachment from or attachment thereof to the invalid chair.

The rotary movement of the motor shaft 33 effected from the prime mover 19 is transmitted via the gear 16, such as a differential gear to the driven shaft 15. The driven shaft 15, coaxial with the wheel axles 12 of the larger driving wheels 13 with its coupling parts 17 engages in the coupling parts 18 of the wheel axles 12, so that the rotary movement of the driven shaft 15 is transmitted directly to the wheel axles 12 of the driving wheels 13. The interengaging coupling parts 17, 18 of each side region .of the invalid chair are encased by devices 26 and covered on the outside. A part of the clamping device 26 thus acts as a support for the hollow shaft 27 enclosing the driven shaft 15 and hence for the whole propulsion unit 14. The propulsion unit 14 can be separated from the wheel axles 12 by detaching the turnbuckles 26, the unit 14, with the coupling parts 17 of its driven shaft 15, being pulled out of the coupling parts 18 of the wheel axles 12. Removal from or insertion of the propulsion unit 14 into the coupling parts 18 of the wheel axles 12 is simple and can be effected with few manipulations and little effort.

The invalid chair is preferably provided with a propulsion unit operating reliably and is favorably arranged in a simple structure which is arranged coaxially to the wheel axles and transmits its rotary movement directly to the wheel axles.

A particularly favorable feature is the detachable arrangement of the propulsion unit whereby the invalid chair can be used both as a mechanically electrically operable chair and as a manually propelled chair. With the propulsion unit removed, the chair is readily and quickly folded up thereby economizing in space. The propulsion unit is of compact design and occupies only a relatively small space below the seat surface of the invalid chair.

In the embodiment of the present invention shown in FIG. 5, two side frames 50, 51 rotatably hold two driving wheels 52 and two steering wheels 52a. The frames 50, 51 are maintained at a variable distance from each other by scissor-action rods 53 and make the invalid chair of the present invention foldable.

The scissor-action rods 53 have two connecting struts 55 which are pivotable about a centre axis 54 and are pivotably connected by their ends to the two frames 50, 51 below the axis 54, and their ends disposed about the axis 54 are held to move upwardly and downwardly in guides 57 on the frames 50, 51 in the vicinity in which a seat 56 extends.

The driving wheels 52, which are greater in diameter than the steering wheels 52a are rotatably held by their axles 58 in horizontal bearings 58a secured to the side frames 50, 51. The smaller steering wheels 52a are mounted by laterally pivotable bearing means, for example, wheel forks 52b, in vertical bearings 52c secured to the frames 50, 51. The steering wheels 52a are thus pivotable about vertical axles (bearings 520) for steering purposes.

The smaller steering wheels 52amay be arranged in front of or behind the driving wheels 52 in the direction of travel of the invalid wheel chair.

A removable propulsion drive 59 is provided between the two side frames '50, 51, below the. seat 56, and is coupled to the two co-axial axles 58 of the driving wheels 52.

The propulsion drive 59 is fitted with an electric motor 60 and a gear transmission 61 and has a driving shaft 62 extending from either side of the drive 59. A coupling member 63, 65 is provided on each of thetwo ends of the driving shaft 62. in addition, each axle 58 of the two driving wheels 52 is provided with a coupling member 64, 66 constructed as a counterpart to the members 63, 65 respectively. Each pair of respective coupling members 63', 64 and 65, 66 axially interengage to provide a clutch. Linchpins 67, 68 are provided to couple members 63, 64 and 65, 66 together. The pins of one clutch are made axially displaceable, and are held spring-loaded in the engaged position. One of the two coupling members 63,64; 65,66 of each clutch is formed from resilient material capable of withstanding torsion forces. It is preferable to make the coupling member 64, 66, which receives insertion apertures 69, resilient.

In the embodiment illustrated in FIGS. 5-9, the driving shaft 62 of the propulsion drive 59 engages detachably on one side of said drive in a coupling member which is rigidly connected to a driving axle 58 by linchpins 67, the pins 67 being held against a coupling member 62 by spring loading. The pin 67 is displaceable' in the direction of the driving axle or at an angle to the direction of the driving axle. On the other side of the 'propulsion drive the shaft 62 is detachably inserted in a coupling member 66 which is rigidly connected to the other driving axle 58, by linchpins 68 undisplaceably mounted on a coupling member 65. It is preferable to construct the two coupling members 64,66 on the axle of resilient material.

The coupling member 63 of one clutch provided on the driving shaft 62 is formed, for example, by a rib firmly but detachably connected to the ends of the driving shaft, and preferablyvextending at a right angle to the longitudinal axis of the driving shaft. Two relatively opposed guide sleeves 70 extending on both sides of the driving shaft 62 are mounted on the rib by means of linchpins 67-displaceable therein. The two linchpins 67 are displaceable parallel to the driving shaft 62 and are each held in the coupled position by respective compression springs 71, such as helical springs. A clamping pin 73 displaceably engages at least in one slit 72 of the guide sleeve 70, and, on the one hand, serves as an abutment for the spring 71 and, on the other hand, enables the particular linchpin 67 to be secured in its uncoupled position. At the same time, the linchpin 67, provided with a knob 74, is displaced against the action of the spring in the sleeve 70 until the clamping pin 73 appears out of the sleeve 70. By axial rotation of the linchpin 67 the pin 73 comes out of the region of the slit or slits in the sleeves 70 and becomes disposed against the free end of the guide sleeve 70 while retaining the linchpin 67 in its displaced position.

The coupling member 64 on the axle is formed by a disc provided with two insertion openings 69 for the linchpins 67. The disc is detachably secured by means of screws 75 on a supporting rib 76 rigidly secured to the axle 58. i

The coupling member 65 of the other clutch on the propulsion drive is also formed by a rib extending'at a right angle to the driving shaft 62 and holding two relatively opposed linchpins 68 provided on each side of the driving shaft 62, in which rib the linchpins 68 are detachably but securely held, for example, by a nut 77 screwed onto its threaded portion. v

The member 66 of the same clutch on the axle, has, corresponding'to the member 64 of the other clutch, the form of a disc with two insertion apertures 69 provided therein and is also detachably secured by screws 75 on a rib 76 rigidly mounted on the driving axle 58.

It is preferable to form the two resilient coupling members 64, 66 of a synthetic material such as rubber or the like, reinforced by a stiffening agent such as a linen and to form insertion apertures 69 of bearing sleeves provided therein. 7

The couplings 63', 65, as are also the ribs 76, are each welded to a sleeve 79 mounted displaceably on the shaft 58 and 62 respectively by wedge means 78.

The propulsion drive '59 is secured against rotation between the two frames 50, 51 by a locking member 81 such as a linchpin which engages in a bearing recess 80, such as a sleeve. The propulsion drive 59 may also be engaged by a locking member 81 in a recess of a frame 50, 51. v

In order to keep the two side frames 50, 51 at a space from each other, a stabilizer rod 82 is provided which is connected by joint members 83 at its end to a joint member 84 such as a spherical head (ball) provided on each frame 50, 51. The joint members 83 may be a spherical recess pivotably mounted on the rod 82. Because of the articulated connection between the stabilizer rod 82 and the frame 50, 51, the invalid wheel chair is flexibly secured at these connecting points. in addition, the rod 82 ensures that the gauge of the wheel chair is reliable.

The removal of the propulsion drive 59 is effected in the following sequence;

The stabilizer rod 82 is jerked upwardly out of its articulated bearings 84 in the direction of the arrow C.

The two di'splaceable pins 67 are drawn out of the resilient coupling member 64 and locked in the drawn-out position by the clamping pin or the two pins 73 turned through approximately 90 and disposed against the guide sleeve 70.

In order to prevent the propulsion drive 59 dropping down, said drive 59 must 'be gripped by its knob 59a with one hand when the coupling pins 67 are withdrawn. If the coupling pins 67 are locked, the propulsion drive 59 is lowered by its released side downwardly and drawn by this released side in the direction of the adjacent driving wheel 52 with the result that the other rigid coupling pins 68 slides out of the coupling member 66 of the other clutch. To make fitting of the propulsion drive 59 easy, the undisplaceable coupling pins 68 have to be introduced in the member 66 at an incline from below, the propulsion drive 59 is then raised to the horizontal position and the locked coupling pins 67 are released so that they can slide into their guide pins 70.

Then, by turning the driving wheel 52 adjacent to this clutch, the coupling pin 67 slides automatically into the insertion apertures 69 of the coupling member 64 by the force of the spring. The stabilizer rod 82 can now be pressed into its pivot bearings 84 again. During the fitting of the supporting drive 59, the drive is reliably secured against rotation by the locking means 81 engaging in its bearing recess 80. When the propulsion drive 59 is operated, the two clutches rotate with the axles 62 and 58 connecting them.

What is claimed is;

l. A foldable wheel chair comprising two side frames, a seat supported by said side frames, scissor-action links hingedly connecting said side frames, horizontal bearings mounted on each side frame, two driving wheels, the axle of each driving wheel being mounted in each horizontal bearing, vertical bearings mounted on each side frame, a laterally pivotable bearing means mounted in eachof said vertical bearings, two dirigible wheels, the axles of said dirigible wheels being mounted in said bearing means, first coupling meansprovided on the axles of said driving wheels and facing the axis of symmetry of said wheel chair, a propulsion drive detachably mounted between said side frames, said propulsion drive having an electric motor in a removable unit as prime mover, second coupling means drivingly connected to said propulsion drive, axial coupling members engaging in said first and second coupling means such that said first and second coupling means are drivingly connected, positioning means provided on one of said side frames to prevent said propulsion drive from rotating with respect to said side frames, a'driving shaft detachably engaging one of said first-coupling means on one side of the propulsion drive, at least one of said axial coupling members being spring loaded against one of said first coupling means and displaceable in the direction of the propulsion drive, each of said first coupling means being rigidly connected to an axle of said driving wheels and formed from resilient material capable of withstanding torsion forces, each of said second coupling means being formed of a rib which is secured to the axial coupling member, and extends at a right angle to the longitudinal axis of the driving shaft, two oppositely disposed guide sleeves being provided on each side of said driving shaft, a pin with a knob being held in the engaged position in said sleeves by a compression spring, the pin being lockable in the uncoupled position, at least one slit being provided in each sleeve, a clamping pin engaging in said at least one slit, said clamping pin serving as an abutment for the compression spring, each of said first coupling means being formed by a disc having two insertion apertures for said pins, a supporting rib being rigidly secured to each driving wheel axle, each of said first coupling means being detachably secured to said supporting rib.

2. A foldable invalid wheel chair as recited in claim 1 wherein the other of said second coupling means is formed by a rib extending at rightangles to the driving shaft, two clutch pins being provided and disposed oppositely to each other on each side of the driving shaft and wherein said first coupling means which interengages said other of said second coupling means is formed of a disc having two insertion apertures, said disc being detachably secured by screws on said rib.

3. A foldable invalid wheel chair, as recited in claim 2 wherein said first coupling means are formed of synthetic material provided with linen reinforcing means.

4. A foldable invalid chair as recited in claim 2 wherein said first coupling means are formed of rubber provided with linen reinforcing means.

5. A foldable invalid chair as recited in claim 2 further comprising a stabilizer rod detachably arranged between said side frames, first joint members being provided on each of said frames, second joint members being provided on each end of said stabilizer. rod, wherein said first and second joint members interengage to hold said side frames flexibly in relative spaced relationship.

k i i i 

1. A foldable wheel chair comprising two side frames, a seat supported by said side frames, scissor-action links hingedly connecting said side frames, horizontal bearings mounted on each side frame, two driving wheels, the axle of each driving wheel being mounted in each horizontal bearing, vertical bearings mounted on each side frame, a laterally pivotable bearing means mounted in each of said vertical bearings, two dirigible wheels, the axles of said dirigible wheels being mounted in said bearing means, first coupling means provided on the axles of said driving wheels and facing the axis of symmetry of said wheel chair, a propulsion drive detachably mounted between said side frames, said propulsion drive having an electric motor in a removable unit as prime mover, second coupling means drivingly connected to said propulsion drive, axial coupling members engaging in said first and second coupling means such that said first and second coupling means are drivingly connected, positioning means provided on one of said side frames to prevent said propulsion drive from rotating with respect to said side frames, a driving shaft detachably engaging one of said first coupling means on one side of the propulsion drive, at least one of said axial coupling members being spring loaded against one of said first coupling means and displaceable in the direction of the propulsion drive, each of said first coupling means being rigidly connected to an axle of said driving wheels and formed from resilient material capable of withstanding torsion forces, each of said second coupling means being formed of a rib which is secured to the axial coupling member, and extends at a right angle to the longitudinal axis of the driving shaft, two oppositely disposed guide sleeves being provided on each side of said driving shaft, a pin with a knob being held in the engaged position in said sleeves by a compression spring, the pin being lockable in the uncoupled position, at least one slit being provided in each sleeve, a clamping pin engaging in said at least one slit, said clamping pin serving as an abutment for the compression spring, each of said first coupling means being formed by a disc having two insertion apertures for said pins, a supporting rib being rigidly secured to each driving wheel axle, each of said first coupling means being detachably secured to said supporting rib.
 2. A foldable invalid wheel chair as recited in claim 1 wherein the other of said second coupling means is formed by a rib extending at right angles to the driving shaft, two clutch pins being provided and disposed oppositely to each other on each side of the driving shaft and wherein said first coupling means which inter-engages said other of said second coupling means is formed of a disc having two insertion apertures, said disc being detachably secured by screws on said rib.
 3. A foldable invalid wheel chair, as recited in claim 2 wherein said first coupling means are formed of synthetic material provided with linen reinforcing means.
 4. A foldable invalid chair as recited in claim 2 wherein said first coupling means are formed of rubber provided with linen reinforcing means.
 5. A foldable invalid chair as recited in claim 2 further comprising a stabilizer rod detachably arranged between said side frames, first joint members being provided on each of said frames, second joint members being provided on each end of said stabilizer rod, wherein said first and second joint members interengage to hold said side frames flexibly in relative spaced relationship. 